Various diagnostic platforms utilize thermal cycling processes which involve heating of reagents at different temperatures to alter certain properties of the reagents. An example application is Polymerase Chain Reaction (PCR) which is a method used to amplify genetic material for detection and analysis. Analysis speed is especially important in diagnostic applications. For example, shorter analysis time would allow faster turnaround time in identifying infectious diseases, or enable the analysis to take place in the time it takes for a physician's appointment.
Thermal cycling methods generally fall under two categories: stationary and continuous flow. Stationary systems conduct thermal cycling by holding a fixed volume of sample fluid and/or reagents stationary in a chamber while varying the temperature of the chamber to alternately heat and cool the reagents. A disadvantage of this kind of thermal cycling is reduced amplification efficiency due to heating and cooling ramping rates associated with varying the chamber temperature during each cycle. Continuous flow systems, on the other hand, conduct thermal cycling by allowing fluid samples to flow through different temperature regions. In particular, each temperature region maintains a distinct temperature and reagents are allowed to pass through the temperature regions for a number of cycles by propelling them, using pumps, to flow through a long channel having sections formed on each temperature region. Delay in inter-temperature transition time can be reduced by controlling the flow rate of fluids within the channel. As a result, continuous flow systems can shorten analysis times compared to stationary thermal cycling.
A number of micro-fluidic approaches to diagnostic applications utilizing continuous flow thermal cycling have been developed for lab-on-a-chip and point-of-care devices. Micro-fluidic devices manipulate microscopic volumes of liquid inside micro-sized structures. As such, it can provide advantages over conventional and non-micro-fluidic based techniques such as smaller sample volumes, greater efficiency of chemical reagents, high speed analysis, high throughput, portability and low production costs per device allowing for disposability.
Micro-fluidic modules can be built by combining several components like channels, connectors, filters, mixers, heaters, sensors, micro-valves, micro-fluidic pumps, and etc. Among these components, it is well known to be difficult to attain micro-fluidic pumps which are ready to be assembled with micro-fluidic devices at low costs. For example, while a range of micro-fluidic devices have been miniaturized to the size of a postage stamp, these devices have often required large external pumping systems for fluid transport through channels. Unfortunately, the inclusion of these external pumps presents added complexity in coupling with fluidic channels, and also often increases the overall size of the micro-fluidic system.
Thus, there is a need for a micro-fluidic system which integrates together functional modules, such as pumps and micro-fluidic structures, to provide reliable and even smaller device footprint for point-of-care diagnostic and lab-on-a-chip applications. Additional benefits and alternatives are also sought when devising solutions.